In April, the athletics body introduced new “eligibility regulations for female classification” that restricted the testosterone levels of for female athletes in the 400m, hurdles, 800m, 1 500m and combined events. Under the rules, athletes who have a “difference of sexual development” would have to ensure their circulating testosterone level remains under 5nmol/L.
Athletes who exceeded the limit would have to alter their bodies by medical means if they wished to compete at international events.

The restrictions would severely impact Semenya in particular, who as things stand would be unable compete in the 800m and 1500m without undergoing medical interventions. In a press statement released on Monday, she described them as “discriminatory, irrational, unjustifiable”.

“I am very upset that I have been pushed into the public spotlight again,” she said. “I don’t like talking about this new rule. I just want to run naturally, the way I was born. It is not fair that I am told I must change. It is not fair that people question who I am. I am Mokgadi Caster Semenya. I am a woman and I am fast.”

Semenya’s legal team will ask the CAS to declare the new rules as discriminatory. In the interim, the athlete will ask the IAAF to suspend the regulations pending her the results of her case as women who wish to compete after November 1 must demonstrate lowered testosterone levels for six months prior.

Her lawyer, Gregory Nott, said: “This is a landmark case concerning international human rights and discrimination against women athletes with major consequences for gender rights which are jealously protected by the South African Bill of Rights.”

Semenya’s challenge comes on the back of a promise by Athletics South Africa last month to engage with the IAAF and approach the CAS if necessary.